Comment 1 for bug 1588198

One fix:

Change:
    def solar_depression(self, depression):
        if isinstance(depression, str):

to:
    def solar_depression(self, depression):
        if isinstance(depression, str) or isinstance(depression, unicode):

---

Another fix:

Add as first import:
from __future__ import unicode_literals

In latitude(self, latitude), longitude(self, longitude), solar_depression(self, depression):

Change:
        if isinstance(depression, str):

to:
        if isinstance(depression, unicode):

---

For both, there may be other similar changes to make elsewhere in the code; tests should find them.