code: def param_dict_to_str(data):
      
      if data is None or not data:
          return ""
      pairs = []
      for key, val in data.items():
          if isinstance(val, (list, tuple, set)) or is_numpy_1d_array(val):
              pairs.append(str(key) + '=' + ','.join(map(str, val)))
          elif isinstance(val, string_type) or isinstance(val, numeric_types) or is_numeric(val):
              pairs.append(str(key) + '=' + str(val))
          elif val is not None:
              raise TypeError('Unknown type of parameter:%s, got:%s'
                              % (key, type(val).__name__))
      return ' '.join(pairs)
docs: Convert Python dictionary to string, which is passed to C API.