<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _decode_quadratic_biases(quadratic_string, edgelist):
 """Inverse of _serialize_quadratic_biases Args: quadratic_string (str) : base 64 encoded string of little endian 8 byte floats, one for each of the edges. Returns: edge is of the form (node1, node2). Example: {(0, 1):
 -1.0, (0, 2):
 0.4, (1, 2):
 1.0} """

    quadratic_bytes = base64.b64decode(quadratic_string)
    return {tuple(edge): bias for edge, bias in zip(edgelist,
            struct.unpack('<' + 'd' * (len(quadratic_bytes) // 8), quadratic_bytes))}