docs: def circuit_to_quirk_url(circuit: circuits.Circuit,
                           prefer_unknown_gate_to_failure: bool=False,
                           escape_url=True) -> str:
      """Returns a Quirk URL for the given circuit.
  
      Args:
          circuit: The circuit to open in Quirk.
          prefer_unknown_gate_to_failure: If not set, gates that fail to convert
              will cause this function to raise an error. If set, a URL
              containing bad gates will be generated. (Quirk will open the URL,
              and replace the bad gates with parse errors, but still get the rest
              of the circuit.)
          escape_url: If set, the generated URL will have special characters such
              as quotes escaped using %. This makes it possible to paste the URL
              into forums and the command line and etc and have it properly
              parse. If not set, the generated URL will be more compact and human
              readable (and can still be pasted directly into a browser's address
              bar).
  
      Returns:
  
      """
      circuit = circuit.copy()
      linearize_circuit_qubits(circuit)
  
      cols = []  # Type: List[List[Any]]
      for moment in circuit:
          can_merges = []
          for op in moment.operations:
              for col, can_merge in _to_quirk_cols(
                      op,
                      prefer_unknown_gate_to_failure):
                  if can_merge:
                      can_merges.append(col)
                  else:
                      cols.append(col)
          if can_merges:
              merged_col = [1] * max(len(e) for e in can_merges)
              for col in can_merges:
                  for i in range(len(col)):
                      if col[i] != 1:
                          merged_col[i] = col[i]
              cols.append(merged_col)
  
      circuit_json = json.JSONEncoder(ensure_ascii=False,
                                      separators=(',', ':'),
                                      sort_keys=True).encode({'cols': cols})
      if escape_url:
          suffix = urllib.parse.quote(circuit_json)
      else:
          suffix = circuit_json
      return 'http://algassert.com/quirk#circuit={}'.format(suffix)