# Use the cool variable as a two state latch which will be True
# whenever inside a json block and False outside of it.
cool = False
with open('input.log') as fh:
   for line in fh:
       if not cool:
           if line.startswith('{'):  # or some other expression triggering
                                     # the start of a json block
               cool = True
               print line
       else:
           print line   # This has json
           if line.startswith('}'):   # end of json
               cool = False