<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def get_error_at(self, cursor):
 """Return error at position `cursor`."""

        for error in self._errors:
            if error.includes(self._vim.eval("expand('%:p')"), cursor):
                return error
        return None