TypeError: int() argument must be a string, a bytes-like object or a number, not 'QVariant'

Because QGIS opens MS Excell tables with string type only, in processing plugin I need to use any field types.

def deg2dms(degree):
    deg = degree
    d = int(deg)
    m = int((deg - d) * 60)
    s = float(((deg - d) * 60 - m) * 60)
    return "{}°{}'{}''".format(d, m, round(s, 2))

But code executes with error:

d = int(deg) TypeError: int() argument must be a string, a bytes-like object or a number, not 'QVariant'

How to convert type QVariant to float?