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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 show(cmap, var, vmin=None, vmax=None):
    '''Show a colormap for a chosen input variable var side by side with
    black and white and jet colormaps.

    :param cmap: Colormap instance
    :param var: Variable to plot.
    :param vmin=None: Min plot value.
    :param vmax=None: Max plot value.

    '''

    # get variable data
    lat, lon, z, data = read(var)

    fig = plt.figure(figsize=(16, 12))

    # Plot with grayscale
    ax = fig.add_subplot(3, 1, 1)
    map1 = ax.scatter(lon, -z, c=data, cmap='gray', s=10, linewidths=0., vmin=vmin, vmax=vmax)
    plt.colorbar(map1, ax=ax)

    # Plot with jet
    ax = fig.add_subplot(3, 1, 2)
    map1 = ax.scatter(lon, -z, c=data, cmap='jet', s=10, linewidths=0., vmin=vmin, vmax=vmax)
    plt.colorbar(map1, ax=ax)

    # Plot with cmap
    ax = fig.add_subplot(3, 1, 3)
    map1 = ax.scatter(lon, -z, c=data, cmap=cmap, s=10, linewidths=0., vmin=vmin, vmax=vmax)
    ax.set_xlabel('Longitude [degrees]')
    ax.set_ylabel('Depth [m]')
    plt.colorbar(map1, ax=ax)

    plt.suptitle(var)