def get_defrange(def_node):
    """
    def_node:    An ast.FunctionDefinition node with start/end position annotations
                 from the asttokens library.
    """
    def_startline = def_node.first_token.start[0] - 1
    def_endline = def_node.last_token.end[0]
    defrange = [def_startline, def_endline]
    return defrange
