code: def json_to_string(self, source):
          
          try:
              load_input_json = json.dumps(source)
          except ValueError as e:
              raise JsonValidatorError("Could serialize '%s' to JSON: %s" % (source, e))
          return load_input_json
docs: Serialize JSON structure into string.
  
          *Args:*\n
          _source_ - JSON structure
  
          *Returns:*\n
          JSON string
  
          *Raises:*\n
          JsonValidatorError
  
          *Example:*\n
          | *Settings* | *Value* |
          | Library    | JsonValidator |
          | Library    | OperatingSystem |
          | *Test Cases* | *Action* | *Argument* | *Argument* |
          | Json to string  | ${json_string}=   | OperatingSystem.Get File |   ${CURDIR}${/}json_example.json |
          |                 | ${json}= | String to json |   ${json_string} |
          |                 | ${string}=  |  Json to string  |  ${json} |
          |                 | ${pretty_string}=  |  Pretty print json  |  ${string} |
          |                 | Log to console  |  ${pretty_string} |