<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def tmybasename(usaf):
 """Basename for USAF base. Args: usaf (str):
 USAF code Returns: (str) """

    url_file = open(env.SRC_PATH + '/tmy3.csv')
    for line in url_file.readlines():
        if line.find(usaf) is not -1:
            return line.rstrip().partition(',')[0]