How to use 'python square root' in Python

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def square_root(self):
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    """
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    Return square root, which is a complex number.
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    EXAMPLES:
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        sage: i = ComplexField(100).0
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        sage: (-i).sqrt()
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        0.70710678118654752440084436210459 - 0.70710678118654752440084436210459*I
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    """
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    return self.sqrt()

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def square_root_mod_p(a, p):
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    """
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    Iterator yielding values v s.t. v * v % p == a
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    There will be 0 or 2 answers.
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    """
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    # see http://course1.winona.edu/eerrthum/13Spring/SquareRoots.pdf
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    a %= p
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    if p == 2:
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        yield a & 1
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        return
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    if p == 4:
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        a &= 3
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        if a == 0:
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            yield 0
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        if a == 1:
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            yield 1
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            yield 3
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        return
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    if p & 3 == 3:
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        s1 = pow(a, (p + 1) >> 2, p)
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        if s1 * s1 % p == a:
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            yield s1
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            yield p - s1
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        return
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    if p & 7 == 5:
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        k = (p - 5) >> 3
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        v1 = pow(a, (p-1) >> 2, p)
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        v2 = pow(a, k+1, p)
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        if v1 == 1:
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            yield v2
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            yield p - v2
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        elif v1 == p-1:
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            r = (v2 * pow(2, 2*k+1, p)) % p
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            yield r
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            yield p - r
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        return
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    else:
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        raise ValueError("not implemented for prime %d" % p)