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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 extract_density(population, plane='xy', bins=100, neurite_type=NeuriteType.basal_dendrite):
    '''Extracts the 2d histogram of the center
       coordinates of segments in the selected plane.
    '''
    segment_midpoints = get_feat('segment_midpoints', population, neurite_type=neurite_type)
    horiz = segment_midpoints[:, 'xyz'.index(plane[0])]
    vert = segment_midpoints[:, 'xyz'.index(plane[1])]
    return np.histogram2d(np.array(horiz), np.array(vert), bins=(bins, bins))