How do you download a Python program from a PC into a Casio CG50?

[StephenG1CMZ]

[edited]
I thought I had cut-and-pasted ztime into ztime.py on the pc, but on the Casio it arrived as ztime~1.py.txt, of unrecognised type.

Investigating, the PC wasn't showing filetypes, and what it showed as ztime.py was in truth time.py.txt.

Old tricks like right-click/rename were ignored, but once the PC was persuaded to show and edit the filetype, it was transferred ok.
Not sure of the exact keystrokes