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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 concatenate_not_none(l, axis=0):
 """Construct a numpy array by stacking not-None arrays in a list Parameters data : list of arrays The list of arrays to be concatenated. Arrays have same shape in all but one dimension or are None, in which case they are ignored. axis : int, default = 0 Axis for the concatenation Returns ------- data_stacked : array The resulting concatenated array. """

    # Get the indexes of the arrays in the list
    mask = []
    for i in range(len(l)):
        if l[i] is not None:
            mask.append(i)

    # Concatenate them
    l_stacked = np.concatenate([l[i] for i in mask], axis=axis)
    return l_stacked