':param ast_node: AST node that originated this scope
:param parent_scope: Parent scope
:param builtins: Language\'s builtin variables'

def __init__(self, ast_node, parent_scope=None, builtins={}):

    self._ast_node = ast_node
    self._parent_scope = parent_scope
    self._builtins = builtins
    self._vars = {}
