def _cast_params_from(params, context, schemas):
 result = {}
 for name in params:
  param_schema = {}
  for schema in schemas:
   if (name in schema):
    param_schema = schema[name]
  result[name] = _cast(context[name], param_schema)
 return result

def _cast_params_from ( params , context , schemas ) : result = { } for name in params : param_schema = { } for schema in schemas : if ( name in schema ) : param_schema = schema [ name ] result [ name ] = _cast ( context [ name ] , param_schema ) return result
pick a list of parameters from context and cast each of them according to the schemas provided .