Construct a piecewise polynomial in the power basis from a polynomial in Bernstein basis.
bp : BPoly
A Bernstein basis polynomial, as created by BPoly
extrapolate : bool or ‘periodic’, optional
If bool, determines whether to extrapolate to out-of-bounds points based on first and last intervals, or to return NaNs. If ‘periodic’, periodic extrapolation is used. Default is True.