def _get_float(data, position, dummy0, dummy1, dummy2):
 end = (position + 8)
 return (_UNPACK_FLOAT(data[position:end])[0], end)

def _get_float ( data , position , dummy0 , dummy1 , dummy2 ) : end = ( position + 8 ) return ( _UNPACK_FLOAT ( data [ position : end ] ) [ 0 ] , end )
decode a bson double to python float .