Mbpp/11

def remove_Occ(s: str, ch: str) -> str:
    """
    Remove the first and last occurrence of the given character from the string.
    If the character appears only once, that single occurrence is removed.
    If the character does not appear, the original string is returned.
    """
    first = s.find(ch)
    last = s.rfind(ch)
    
    # character not found
    if first == -1:
        return s
    
    # If there is only one occurrence (first == last), remove it once
    if first == last:
        return s[:first] + s[first+1:]
    
    # Remove the last occurrence first to keep the first index valid,
    # then remove the first occurrence.
    # Remove last
    s = s

• ['hello', 'l']

• ['aaa', 'a']