code: def time_to_readable_str(value_us, force_time_unit=None):
      """Convert time value to human-readable string.
  
      Args:
        value_us: time value in microseconds.
        force_time_unit: force the output to use the specified time unit. Must be
          in TIME_UNITS.
  
      Returns:
        Human-readable string representation of the time value.
  
      Raises:
        ValueError: if force_time_unit value is not in TIME_UNITS.
      """
      if not value_us:
          return "0"
      if force_time_unit:
          if force_time_unit not in TIME_UNITS:
              raise ValueError(
                  "Invalid time unit: %s" % force_time_unit
              )
          order = TIME_UNITS.index(force_time_unit)
          time_unit = force_time_unit
          return "{:.10g}{}".format(
              value_us / math.pow(10.0, 3 * order), time_unit
          )
      else:
          order = min(
              len(TIME_UNITS) - 1, int(math.log(value_us, 10) / 3)
          )
          time_unit = TIME_UNITS[order]
          return "{:.3g}{}".format(
              value_us / math.pow(10.0, 3 * order), time_unit
          )
  
imports: import math
  import numpy
  from tensorflow.python.debug.cli import command_parser
  from tensorflow.python.debug.cli import debugger_cli_common
  from tensorflow.python.debug.cli import tensor_format
  from tensorflow.python.debug.lib import common
  from tensorflow.python.framework import ops
  from tensorflow.python.framework import tensor
  from tensorflow.python.ops import variables
  from tensorflow.python.platform import gfile
label_desc: Use image node_id 2 for calling a global function with example usage: time_to_readable_str(value_us, force_time_unit) and returns: str, str, str