Validate password

Create a RegExp that represents valid password, like below. 

reg =   "^(?=.*\[a-z\])(?=.*\[A-Z\])(?=.*\\d)(?=.*\[@$!%*#?&\])\[A-Za-z\\d@$!#%*?&\]{6,20}$"

Snippet to validate 

def validate_pw(password)
    pat =   re.compile(reg)
    mat =   re.search(pat, passwd)
    if mat:
        return True
    else:
        return False