562.012.  Attempt — guilt for an offense may be based on. — 1.  Guilt for an offense may be based upon an attempt to commit an offense if, with the purpose of committing the offense, a person performs any act which is a substantial step towards the commission of the offense.  A "substantial step" is conduct which is strongly corroborative of the firmness of the actor's purpose to complete the commission of the offense.

  2.  It is no defense to a prosecution that the offense attempted was, under the actual attendant circumstances, factually or legally impossible of commission, if such offense could have been committed had the attendant circumstances been as the actor believed them to be.

  3.  Unless otherwise set forth in the statute creating the offense, when guilt for a felony or misdemeanor is based upon an attempt to commit that offense, the felony or misdemeanor shall be classified one step lower than the class provided for the felony or misdemeanor in the statute creating the offense.