**BUG**
Concise problem statement:
Should be able to set Z0 and TD or Z0, F and NL.
User options are given as Z0, TD and F but no NL option.
Setting F and adding an NL attribute, then removing TD does not run a simulation because the parameters for T1 and T2 are not set correctly.
Url:
https://easyeda.com/file_view_Transmission-line_aOICUO6oh.htm
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