[Discuss-gnuradio] Python enabler block not working

"""
Embedded Python Blocks:

Each this file is saved, GRC will instantiate the first class it finds to get
ports and parameters of your block. The arguments to __init__ will be the
parameters. All of them are required to have default values!
"""
import numpy as np
import sys
from gnuradio import gr

class blk(gr.sync_block):
def __init__(self, enabler=False): # only default arguments here
gr.sync_block.__init__(
self,
name='Embedded Python Block',
in_sig=[np.float32],
out_sig=[np.float32]
)
self.enabler = enabler

def work(self, input_items, output_items):
key = sys.stdin.read(1)

if key==' ':
self.enabler=True

if self.enabler == True:
output_items[0][:] = input_items[0]
return len(output_items[0])

"""Created by Abdul Samad Usman"""

Hi

I am trying to make a python block that would act as an enabler between audio source and audio sink such that whenever I hit space from my keyboard the transmission begins and should stop after re hitting again. For starters I tried to start the transmission using just only one space hit but even this seems to be failing.I am using python block module from gnuradio. I get the following errors on my report panel. The source code of the block and the GRC screenshot is also attached.


Traceback (most recent call last):
File "/usr/lib/python2.7/dist-packages/gnuradio/gr/gateway.py", line 55, in eval
try: self._callback()
File "/usr/lib/python2.7/dist-packages/gnuradio/gr/gateway.py", line 160, in __gr_block_handle
) for i in self.__out_indexes],
TypeError: in method 'block_gw_message_type_work_args_return_value_set', argument 2 of type 'int'
thread[thread-per-block[1]: <block Embedded Python Block (1)>]: SWIG director method error. Error detected when calling 'feval_ll.eval'

If anybody figure out the problem or its probable solution please let me know

Regards
Abdul Samad