code: def timedelta_to_str(td: pd.Timedelta) -> str:
      """Construct a tight string representation for the given timedelta arg.
  
      Parameters
      ----------
      td: pd.Timedelta
          The timedelta for which the string representation is constructed
  
      Returns
      -------
      str:
          The tight string bounds of format '$d-$h$m$s.$ms'.
  
      """
      out_str = ""
  
      # Edge case if we deal with negative
      if td < pd.Timedelta(seconds=0):
          td *= -1
          out_str += "NEG"
  
      # Note: this must happen after the *= -1
      c = td.components
      if c.days > 0:
          out_str += f"{c.days}D"
      if (
          c.hours > 0
          or c.minutes > 0
          or c.seconds > 0
          or c.milliseconds > 0
      ):
          out_str += "_" if len(out_str) else ""
  
      if c.hours > 0:
          out_str += f"{c.hours}h"
      if c.minutes > 0:
          out_str += f"{c.minutes}m"
      if c.seconds > 0 or c.milliseconds > 0:
          out_str += f"{c.seconds}"
          if c.milliseconds:
              out_str += f".{str(c.milliseconds / 1000).split('.')[-1].rstrip('0')}"
          out_str += "s"
      return out_str
  
imports: from typing import Union
  import pandas
label_desc: Use image node_id 1 for calling a global function with example usage: timedelta_to_str(td) and returns: out_str