It is unlawful for any person or firm to engage in the business or occupation of pruning, treating or removing street or park trees within the city without first applying for and procuring a license. The license fee shall be fifteen dollars ($15.00) annually, paid in advance; provided, however, that no license shall be required of any public service company or city employee doing such work in the pursuit of their public service endeavors. Before any license is issued, each applicant shall first file evidence of possession of liability insurance in the minimum amounts of twenty five thousand dollars ($25,000.00) for bodily injury and two hundred fifty thousand dollars ($250,000.00) property damage, indemnifying the city or any person injured or damaged resulting from the pursuit of such endeavors as herein described. (1991 Code § 12.16.140, as amended)