NewParamParser receives a "src" of a single parameter and returns a new ParamParser, ready to Parse.

Parse takes a route "fullpath" and returns its param statements or an error if failed.

DefaultParamErrorCode is the default http error code, 404 not found, per-parameter.

ParamParser is the parser which is being used by the Parse function to parse path segments one by one and return their parsed parameter statements (param name, param type its functions and the inline route's functions).