def __init__(self,<EOL>name,<EOL>data_type,<EOL>doc,<EOL>ast_node):
super(StructField, self).__init__(name, data_type, doc, ast_node)<EOL>self.has_default = False<EOL>self._default = None<EOL>
Creates a new Field.

:param str name: Name of the field.
:param Type data_type: The type of variable for of this field.
:param str doc: Documentation for the field.
:param ast_node: Raw field definition from the parser.
:type ast_node: stone.frontend.ast.AstField