"""Classes and methods for working with PDA stacks."""


class PDAStack(object):
    """A PDA stack."""

    def __init__(self, stack, **kwargs):
        """Initialize the new PDA stack."""
        if isinstance(stack, PDAStack):
            self._init_from_stack_obj(stack)
        else:
            self.stack = list(stack)

    def _init_from_stack_obj(self, stack_obj):
        """Initialize this Stack as a deep copy of the given Stack."""
        self.__init__(stack_obj.stack)

    def top(self):
        """Return the symbol at the top of the stack."""
        if self.stack:
            return self.stack[-1]
        else:
            return ''

    def pop(self):
        """Pop the stack top from the stack."""
        self.stack.pop()

    def replace(self, symbols):
        """
        Replace the top of the stack with the given symbols.

        The first symbol in the given sequence becomes the new stack top.
        """
        self.stack.pop()
        self.stack.extend(reversed(symbols))

    def copy(self):
        """Return a deep copy of the stack."""
        return self.__class__(self)

    def __len__(self):
        """Return the number of symbols on the stack."""
        return len(self.stack)

    def __iter__(self):
        """Return an interator for the stack."""
        return iter(self.stack)

    def __repr__(self):
        """Return a string representation of the stack."""
        return '{}({})'.format(self.__class__.__name__, self.stack)

    def __eq__(self, other):
        """Check if two stacks are equal."""
        return self.__dict__ == other.__dict__

"""Classes and methods for working with PDA stacks."""


class PDAStack(object):
    """A PDA stack."""

    def __init__(self, stack):
        """Initialize the new PDA stack."""
        self.stack = list(stack)

    def top(self):
        """Return the symbol at the top of the stack."""
        if self.stack:
            return self.stack[-1]
        else:
            return ''

    def pop(self):
        """Pop the stack top from the stack."""
        self.stack.pop()

    def replace(self, symbols):
        """
        Replace the top of the stack with the given symbols.

        The first symbol in the given sequence becomes the new stack top.
        """
        self.stack.pop()
        self.stack.extend(reversed(symbols))

    def copy(self):
        """Return a deep copy of the stack."""
        return self.__class__(**self.__dict__)

    def __len__(self):
        """Return the number of symbols on the stack."""
        return len(self.stack)

    def __iter__(self):
        """Return an interator for the stack."""
        return iter(self.stack)

    def __repr__(self):
        """Return a string representation of the stack."""
        return '{}({})'.format(self.__class__.__name__, self.stack)

    def __eq__(self, other):
        """Check if two stacks are equal."""
        return self.__dict__ == other.__dict__

Remove copy constructor for PDAStack
Remove copy constructor for PDAStack

The copy() method is already sufficient.

  """Classes and methods for working with PDA stacks."""
  
  
  class PDAStack(object):
      """A PDA stack."""
  
-     def __init__(self, stack, **kwargs):
+     def __init__(self, stack):
          """Initialize the new PDA stack."""
-         if isinstance(stack, PDAStack):
-             self._init_from_stack_obj(stack)
-         else:
-             self.stack = list(stack)
+         self.stack = list(stack)
- 
-     def _init_from_stack_obj(self, stack_obj):
-         """Initialize this Stack as a deep copy of the given Stack."""
-         self.__init__(stack_obj.stack)
  
      def top(self):
          """Return the symbol at the top of the stack."""
          if self.stack:
              return self.stack[-1]
          else:
              return ''
  
      def pop(self):
          """Pop the stack top from the stack."""
          self.stack.pop()
  
      def replace(self, symbols):
          """
          Replace the top of the stack with the given symbols.
  
          The first symbol in the given sequence becomes the new stack top.
          """
          self.stack.pop()
          self.stack.extend(reversed(symbols))
  
      def copy(self):
          """Return a deep copy of the stack."""
-         return self.__class__(self)
+         return self.__class__(**self.__dict__)
  
      def __len__(self):
          """Return the number of symbols on the stack."""
          return len(self.stack)
  
      def __iter__(self):
          """Return an interator for the stack."""
          return iter(self.stack)
  
      def __repr__(self):
          """Return a string representation of the stack."""
          return '{}({})'.format(self.__class__.__name__, self.stack)
  
      def __eq__(self, other):
          """Check if two stacks are equal."""
          return self.__dict__ == other.__dict__
  
Remove copy constructor for PDAStack
## Code Before:
"""Classes and methods for working with PDA stacks."""


class PDAStack(object):
    """A PDA stack."""

    def __init__(self, stack, **kwargs):
        """Initialize the new PDA stack."""
        if isinstance(stack, PDAStack):
            self._init_from_stack_obj(stack)
        else:
            self.stack = list(stack)

    def _init_from_stack_obj(self, stack_obj):
        """Initialize this Stack as a deep copy of the given Stack."""
        self.__init__(stack_obj.stack)

    def top(self):
        """Return the symbol at the top of the stack."""
        if self.stack:
            return self.stack[-1]
        else:
            return ''

    def pop(self):
        """Pop the stack top from the stack."""
        self.stack.pop()

    def replace(self, symbols):
        """
        Replace the top of the stack with the given symbols.

        The first symbol in the given sequence becomes the new stack top.
        """
        self.stack.pop()
        self.stack.extend(reversed(symbols))

    def copy(self):
        """Return a deep copy of the stack."""
        return self.__class__(self)

    def __len__(self):
        """Return the number of symbols on the stack."""
        return len(self.stack)

    def __iter__(self):
        """Return an interator for the stack."""
        return iter(self.stack)

    def __repr__(self):
        """Return a string representation of the stack."""
        return '{}({})'.format(self.__class__.__name__, self.stack)

    def __eq__(self, other):
        """Check if two stacks are equal."""
        return self.__dict__ == other.__dict__

## Instruction:
Remove copy constructor for PDAStack
## Code After:
"""Classes and methods for working with PDA stacks."""


class PDAStack(object):
    """A PDA stack."""

    def __init__(self, stack):
        """Initialize the new PDA stack."""
        self.stack = list(stack)

    def top(self):
        """Return the symbol at the top of the stack."""
        if self.stack:
            return self.stack[-1]
        else:
            return ''

    def pop(self):
        """Pop the stack top from the stack."""
        self.stack.pop()

    def replace(self, symbols):
        """
        Replace the top of the stack with the given symbols.

        The first symbol in the given sequence becomes the new stack top.
        """
        self.stack.pop()
        self.stack.extend(reversed(symbols))

    def copy(self):
        """Return a deep copy of the stack."""
        return self.__class__(**self.__dict__)

    def __len__(self):
        """Return the number of symbols on the stack."""
        return len(self.stack)

    def __iter__(self):
        """Return an interator for the stack."""
        return iter(self.stack)

    def __repr__(self):
        """Return a string representation of the stack."""
        return '{}({})'.format(self.__class__.__name__, self.stack)

    def __eq__(self, other):
        """Check if two stacks are equal."""
        return self.__dict__ == other.__dict__
