mypy: Extract addressee.stream_name() check to satisfy mypy.
mypy: Extract addressee.stream_name() check to satisfy mypy.

zulip/zulip,brainwane/zulip,shubhamdhama/zulip,tommyip/zulip,shubhamdhama/zulip,rht/zulip,synicalsyntax/zulip,zulip/zulip,showell/zulip,brainwane/zulip,synicalsyntax/zulip,shubhamdhama/zulip,shubhamdhama/zulip,zulip/zulip,showell/zulip,eeshangarg/zulip,hackerkid/zulip,tommyip/zulip,punchagan/zulip,synicalsyntax/zulip,andersk/zulip,eeshangarg/zulip,andersk/zulip,synicalsyntax/zulip,kou/zulip,hackerkid/zulip,tommyip/zulip,rishig/zulip,timabbott/zulip,eeshangarg/zulip,rishig/zulip,tommyip/zulip,showell/zulip,timabbott/zulip,timabbott/zulip,brainwane/zulip,punchagan/zulip,synicalsyntax/zulip,eeshangarg/zulip,timabbott/zulip,showell/zulip,andersk/zulip,andersk/zulip,timabbott/zulip,zulip/zulip,shubhamdhama/zulip,kou/zulip,timabbott/zulip,hackerkid/zulip,eeshangarg/zulip,kou/zulip,timabbott/zulip,rht/zulip,hackerkid/zulip,andersk/zulip,kou/zulip,synicalsyntax/zulip,showell/zulip,andersk/zulip,tommyip/zulip,punchagan/zulip,kou/zulip,tommyip/zulip,hackerkid/zulip,rishig/zulip,brainwane/zulip,hackerkid/zulip,shubhamdhama/zulip,showell/zulip,brainwane/zulip,andersk/zulip,rht/zulip,rht/zulip,punchagan/zulip,rishig/zulip,tommyip/zulip,brainwane/zulip,shubhamdhama/zulip,rht/zulip,synicalsyntax/zulip,rht/zulip,zulip/zulip,rishig/zulip,brainwane/zulip,eeshangarg/zulip,rishig/zulip,punchagan/zulip,rht/zulip,eeshangarg/zulip,zulip/zulip,kou/zulip,zulip/zulip,punchagan/zulip,hackerkid/zulip,punchagan/zulip,rishig/zulip,kou/zulip,showell/zulip