code: def theta_str(theta, taustr=TAUSTR, fmtstr='{coeff:,.1f}{taustr}'):
      r
      coeff = theta / TAU
      theta_str = fmtstr.format(coeff=coeff, taustr=taustr)
      return theta_str
docs: r"""
      Format theta so it is interpretable in base 10
  
      Args:
          theta (float) angle in radians
          taustr (str): default 2pi
  
      Returns:
          str : theta_str - the angle in tau units
  
      Example1:
          >>> # ENABLE_DOCTEST
          >>> from utool.util_str import *  # NOQA
          >>> theta = 3.1415
          >>> result = theta_str(theta)
          >>> print(result)
          0.5*2pi
  
      Example2:
          >>> # ENABLE_DOCTEST
          >>> from utool.util_str import *  # NOQA
          >>> theta = 6.9932
          >>> taustr = 'tau'
          >>> result = theta_str(theta, taustr)
          >>> print(result)
          1.1tau