{
  "name": "map_exist",
  "type": "function",
  "description": "Returns true if the given key exists in the map.",
  "arguments": [ {"arg":"map","description":"a map"},
                 {"arg":"key","description":"the key to lookup"}],
  "examples": [ { "expression":"map_exist(map('1','one','2','two'),'3')", "returns":"false"}]
}