What is the test for dissuading a witness and robbery?

Defendant also argues that the counts for dissuading a witness and robbery are unsupported by substantial evidence "[g]iven Ana's lack of credibility and lack of corroboration." However, "unless the testimony is physically impossible or inherently improbable, testimony of a single witness is sufficient to support a conviction." (People v. Young (2005) 34 Cal.4th 1149, 1181.) As discussed above, Ana's testimony was not physically impossible or inherently improbable. Her testimony alone is therefore sufficient to support the convictions for both counts.