1. A person commits a robbery when, having the intent to commit a theft, the person does any of the following acts to assist or further the commission of the intended theft or the person’s escape from the scene thereof with or without the stolen property:
a. Commits an assault upon another.
b. Threatens another with or purposely puts another in fear of immediate serious injury.
c. Threatens to commit immediately any forcible felony.
2. It is immaterial to the question of guilt or innocence of robbery that property was or was not actually stolen.
Definition of forcible felony, §702.11