<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def chk_enum_arg(s):
 """Checks if the string `s` is a valid enum string. Return True or False."""


    if len(s) == 0 or s[0].isspace() or s[-1].isspace():
        return False
    else:
        return True