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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 factor_cmap(field_name, palette, factors, start=0, end=None, nan_color="gray"):
    ''' Create a ``DataSpec`` dict that applies a client-side
    ``CategoricalColorMapper`` transformation to a ``ColumnDataSource``
    column.

    Args:
        field_name (str) : a field name to configure ``DataSpec`` with

        palette (seq[color]) : a list of colors to use for colormapping

        factors (seq) : a sequences of categorical factors corresponding to
            the palette

        start (int, optional) : a start slice index to apply when the column
            data has factors with multiple levels. (default: 0)

        end (int, optional) : an end slice index to apply when the column
            data has factors with multiple levels. (default: None)

        nan_color (color, optional) : a default color to use when mapping data
            from a column does not succeed (default: "gray")

    Returns:
        dict

    '''
    return field(field_name, CategoricalColorMapper(palette=palette,
                                                    factors=factors,
                                                    start=start,
                                                    end=end,
                                                    nan_color=nan_color))