has_assignment

A JSON data stream might sometimes contain an assignment, like:

``` var _json_data = { "member_name" : [ ... ```

even though it would technically constitute a violation of the RFC.

`JsonParser` will ignore the left hand identifier and parse the right hand value of the assignment. `JsonParser` will record, though, the existence of the assignment in the data stream and the variable name used.

Parameters:

this	a parser
variable_name	the variable name

Returns:

`TRUE` if there was an assignment, and `FALSE` otherwise