(self, ind)
Returns basis vector for the provided index, if the index is a string.

        If the index is a number, returns the coordinate variable correspon-
        -ding to that index.
Returns basis vector for the provided index, if the index is a string.
Returns basis vector for the provided index if the index is a string .
def __getitem__(self, ind):
        """
        Returns basis vector for the provided index, if the index is a string.

        If the index is a number, returns the coordinate variable correspon-
        -ding to that index.
        """
        if not isinstance(ind, str):
            if ind < 3:
                return self.varlist[ind]
            else:
                raise ValueError("Invalid index provided")
        if self.indices[0] == ind:
            return self.x
        if self.indices[1] == ind:
            return self.y
        if self.indices[2] == ind:
            return self.z
        else:
            raise ValueError('Not a defined index')
def __getitem__ ( self , ind ) : if not isinstance ( ind , str ) : if ind < 3 : return self . varlist [ ind ] else : raise ValueError ( "Invalid index provided" ) if self . indices [ 0 ] == ind : return self . x if self . indices [ 1 ] == ind : return self . y if self . indices [ 2 ] == ind : return self . z else : raise ValueError ( 'Not a defined index' )