code: def _preprocess(parameters, pattern, wires):
      """Validate and pre-process inputs as follows:
  
      * Check that pattern is recognised, or use default pattern if None.
      * Check the dimension of the parameters
      * Create wire sequence of the pattern.
  
      Args:
          parameters (tensor_like): trainable parameters of the template
          pattern (str): specifies the wire pattern
          wires (Wires): wires that template acts on
  
      Returns:
          wire_sequence, parameters: preprocessed pattern and parameters
      """
  
      if isinstance(pattern, str):
          _wires = wires
          if pattern not in OPTIONS:
              raise ValueError(f"did not recognize pattern {pattern}")
      else:
          # turn custom pattern into list of Wires objects
          _wires = [Wires(w) for w in pattern]
          # set "pattern" to "custom", indicating that custom settings have to be used
          pattern = "custom"
  
      # check that there are enough parameters for pattern
      if parameters is not None:
          shape = qml.math.shape(parameters)
  
          # expand dimension so that parameter sets for each unitary can be unpacked
          if len(shape) == 1:
              parameters = qml.math.expand_dims(parameters, 1)
  
          # specific error message for ring edge case of 2 wires
          if (
              (pattern == "ring")
              and (len(wires) == 2)
              and (shape[0] != 1)
          ):
              raise ValueError(
                  "the ring pattern with 2 wires is an exception and only applies one unitary"
              )
          num_params = PATTERN_TO_NUM_PARAMS[pattern](_wires)
          if shape[0] != num_params:
              raise ValueError(
                  f"Parameters must contain entries for {num_params} unitaries; got {shape[0]} entries"
              )
  
      wire_sequence = PATTERN_TO_WIRES[pattern](_wires)
      return wire_sequence, parameters
  
imports: import pennylane
  from pennylane.wires import Wires
label_desc: Use image node_id 4 for calling a global function with example usage: _preprocess(parameters, pattern, wires) and returns: wire_sequence,  parameters