Uninstalls the given package (given in pip's package syntax or a tuple of
        ('name', 'ver')) from this virtual environment.

def uninstall(self, package):
        """Uninstalls the given package (given in pip's package syntax or a tuple of
        ('name', 'ver')) from this virtual environment."""
        if isinstance(package, tuple):
            package = '=='.join(package)
        if not self.is_installed(package):
            self._write_to_log('%s is not installed, skipping' % package)
            return
        try:
            self._execute_pip(['uninstall', '-y', package])
        except subprocess.CalledProcessError as e:
            raise PackageRemovalException((e.returncode, e.output, package))