environment/lib/python2.7/site-packages/IPython/utils/warn.py
def warn(msg,level=2,exit_val=1):
    """Standard warning printer. Gives formatting consistency.

    Output is sent to io.stderr (sys.stderr by default).

    Options:

    -level(2): allows finer control:
      0 -> Do nothing, dummy function.
      1 -> Print message.
      2 -> Print 'WARNING:' + message. (Default level).
      3 -> Print 'ERROR:' + message.
      4 -> Print 'FATAL ERROR:' + message and trigger a sys.exit(exit_val).

    -exit_val (1): exit value returned by sys.exit() for a level 4
    warning. Ignored for all other levels."""

    if level>0:
        header = ['','','WARNING: ','ERROR: ','FATAL ERROR: ']
        io.stderr.write('%s%s' % (header[level],msg))
        if level == 4:
            print >> io.stderr,'Exiting.\n'
            sys.exit(exit_val)
def warn(msg,level=2,exit_val=1):
    if level>0:
        header = ['','','WARNING: ','ERROR: ','FATAL ERROR: ']
        io.stderr.write('%s%s' % (header[level],msg))
        if level == 4:
            print >> io.stderr,'Exiting.\n'
            sys.exit(exit_val)
def warn ( msg , level = 2 , exit_val = 1 ) : if level > 0 : header = [ '' , '' , 'WARNING: ' , 'ERROR: ' , 'FATAL ERROR: ' ] io . stderr . write ( '%s%s' % ( header [ level ] , msg ) ) if level == 4 : print >> io . stderr , 'Exiting.\n' sys . exit ( exit_val )
Standard warning printer. Gives formatting consistency.

    Output is sent to io.stderr (sys.stderr by default).

    Options:

    -level(2): allows finer control:
      0 -> Do nothing, dummy function.
      1 -> Print message.
      2 -> Print 'WARNING:' + message. (Default level).
      3 -> Print 'ERROR:' + message.
      4 -> Print 'FATAL ERROR:' + message and trigger a sys.exit(exit_val).

    -exit_val (1): exit value returned by sys.exit() for a level 4
    warning. Ignored for all other levels.
Standard warning printer . Gives formatting consistency .