parameters: (self, name)
return_statement: return name in _ALL_FIELDS
docstring: return True if name is a valid metadata key
docstring_summary: return True if name is a valid metadata key
docstring_tokens: return True if name is a valid metadata key
function: def is_field(self, name):
          """return True if name is a valid metadata key"""
          name = self._convert_name(name)
          return name in _ALL_FIELDS
function_tokens: def is_field ( self , name ) : name = self . _convert_name ( name ) return name in _ALL_FIELDS