def hex_to_rgb(value):
    value = value.lstrip('#')
    lv = len(value)
    return tuple(int(value[i:i + lv // 3], 16) for i in range(0, lv, lv // 3))

def rgb_to_hex(rgb):
    return '#%02x%02x%02x' % rgb
    										# Resultados
print hex_to_rgb("#123456")					# (18, 52, 86)
print hex_to_rgb("#ffffff")					# (255, 255, 255)
print hex_to_rgb("#ffffffffffff")			# (65535, 65535, 65535)
print rgb_to_hex((18, 52, 86))				# #123456
print rgb_to_hex((255, 255, 255))			# #ffffff
print rgb_to_hex((65535, 65535, 65535))		# #ffffffffffff