from itertools import groupby
lines = '''
This is the
first paragraph.

This is the second.
'''.splitlines()
#Use itertools.groupby and bool to return groups of 
# consecutive lines that either have content or don't.

for has_chars, frags in groupby(lines, bool):
	if has_chars:
		print ' '.join(frags)

#PRINTS:
#This is the first paragraph.
#This is the second.