"""Graphical User Interface (GUI) for configuration and database inspection.

The GUI is a leight-weight interface which makes the configuration
of the signac framework and data inspection more straight-forward."""
import warnings
try:
    import PySide  # noqa
except ImportError:
    warnings.warn("Failed to import PySide. "
                  "gui will not be available.", ImportWarning)

    def main():
        """Start signac-gui.

        The gui is only available if PySide is installed."""
        raise ImportError(
            "You need to install PySide to use the gui.")
else:
    from .gui import main

__all__ = ['main']

@@ -259,109 +259,101 @@
 oqa%0A
-except ImportError:%0A    warnings.warn(%22Failed to import PySide. %22%0A                  %22gui will
+    import pymongo  # noqa%0Aexcept ImportError as error:%0A    msg = %22%7B%7D. The signac gui is
  not 
-be 
 avai
@@ -359,16 +359,52 @@
 ilable.%22
+.format(error)%0A    warnings.warn(msg
 , Import
@@ -479,136 +479,69 @@
 gui 
-is only available if PySide is installed.%22%22%22%0A        raise ImportError(%0A            %22You need to install PySide to use the gui.%22
+requires PySide and pymongo.%22%22%22%0A        raise ImportError(msg
 )%0Ael

Remove hard dependency for pymongo.