code: def vol_per_rev_3_stop(color="", inner_diameter=0):
      
      if color != "":
          inner_diameter = ID_colored_tube(color)
      term1 = (R_pump * 2 * np.pi - k_nonlinear * inner_diameter) / u.rev
      term2 = np.pi * (inner_diameter ** 2) / 4
      return (term1 * term2).to(u.mL/u.rev)
docs: Return the volume per revolution of an Ismatec 6 roller pump
      given the inner diameter (ID) of 3-stop tubing. The calculation is
      interpolated from the table found at
      http://www.ismatec.com/int_e/pumps/t_mini_s_ms_ca/tubing_msca2.htm.
  
      Note:
      1. Either input a string as the tubing color code or a number as the
      tubing inner diameter. If both are given, the function will default to using
      the color.
      2. The calculation is interpolated for inner diameters between 0.13 and 3.17
      mm. Accuracy is not guaranteed for tubes with smaller or larger diameters.
  
      :param color: Color code of the Ismatec 3-stop tubing
      :type color: string
      :param inner_diameter: Inner diameter of the Ismatec 3-stop tubing. Results will be most accurate for inner diameters between 0.13 and 3.17 mm.
      :type inner_diameter: float
  
      :return: Volume per revolution output by a 6-roller pump through the 3-stop tubing (mL/rev)
      :rtype: float
  
      :Examples:
  
      >>> from aguaclara.research.peristaltic_pump import vol_per_rev_3_stop
      >>> from aguaclara.core.units import unit_registry as u
      >>> round(vol_per_rev_3_stop(color="yellow-blue"), 6)
      <Quantity(0.148846, 'milliliter / rev')>
      >>> round(vol_per_rev_3_stop(inner_diameter=.20*u.mm), 6)
      <Quantity(0.003116, 'milliliter / rev')>