<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def remove_observations_below_value(x, y, z, val=0):
 r"""Remove all x, y, and z where z is less than val. Will not destroy original values. Parameters x: array_like x coordinate. y: array_like y coordinate. z: array_like Observation value. val: float Value at which to threshold z. Returns ------- x, y, z List of coordinate observation pairs without observation values less than val. """

    x_ = x[z >= val]
    y_ = y[z >= val]
    z_ = z[z >= val]

    return x_, y_, z_