docs: function hasMethod (signature) {
      // convert signature string to method and function name
      signature = getValidSignature(signature)
      // get module
      var module = immutable.modules[signature.moduleName]
      // return false if module does not exist
      if (!defined(module)) {
          return false
      }
      // check if method exists
      return defined(module[signature.methodName]) ? true : false
  }