checking if a string contains a number

[Suresh Jeevanandam]

Hi,
	I have a string like,
	s1 = '12e3'
	s2 = 'junk'

	Now before converting these values to float, I want to check if they 
are valid numbers.

	s1.isdigit returns False.

	Is there any other function which would return True for s1 and False 
for s2.

Thanks

--
Suresh