parameters: (self, key)
return_statement: return key in self._info_axis
docstring: True if the key is in the info axis
docstring_summary: True if the key is in the info axis
docstring_tokens: True if the key is in the info axis
function: def __contains__(self, key):
          """True if the key is in the info axis"""
          return key in self._info_axis
function_tokens: def __contains__ ( self , key ) : return key in self . _info_axis