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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def L_plate_ET(q_plant, W_chan):
 """Return the length of the plates in the entrance tank. Parameters q_plant: float Plant flow rate W_chan: float Width of channel Returns ------- float ? Examples -------- 0.00194 """

    L_plate = (q_plant / (num_plates_ET(q_plant, W_chan) * W_chan *
                          design.ent_tank.CAPTURE_BOD_VEL.magnitude * np.cos(
                design.ent_tank.PLATE_ANGLE.to(u.rad).magnitude)))
    - (design.ent_tank.PLATE_S.magnitude * np.tan(design.ent_tank.PLATE_ANGLE.to(u.rad).magnitude))
    return L_plate