<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def col2hue(r, g, b):
 """Return hue value corresponding to given RGB color."""

    return round2(180 / pi * atan2(sqrt(3) * (g - b), 2 * r - g - b) + 360) % 360