parameters: (self, name)
docstring: Return the subfield of this field named ``name`` or raise
          a :exc:`KeyError` if a subfield does not exist named ``name``.
docstring_summary: Return the subfield of this field named ``name`` or raise
          a :exc:`KeyError` if a subfield does not exist named ``name``.
docstring_tokens: Return the subfield of this field named name or raise a : exc : KeyError if a subfield does not exist named name .
function: def __getitem__(self, name):
          """Return the subfield of this field named ``name`` or raise
          a :exc:`KeyError` if a subfield does not exist named ``name``."""
          for child in self.children:
              if child.name == name:
                  return child
          raise KeyError(name)
function_tokens: def __getitem__ ( self , name ) : for child in self . children : if child . name == name : return child raise KeyError ( name )