AttributeError: 'bytes' object has no attribute 'encode' #9

I see this error while running a project using python3.7:

File "/usr/local/lib/python3.7/site-packages/fdb/fbcore.py", line 845, in connect
no_reserve, db_key_scope, no_gc, no_db_triggers, no_linger)
File "/usr/local/lib/python3.7/site-packages/fdb/fbcore.py", line 773, in build_dpb
dpb.add_string_parameter(isc_dpb_user_name, user)
File "/usr/local/lib/python3.7/site-packages/fdb/fbcore.py", line 633, in add_string_parameter
value = value.encode(charset_map.get(self.charset, self.charset))
AttributeError: 'bytes' object has no attribute 'encode'