use decimal to convert string to float

gistfile1.py

from decimal import *

if 'x' in request.params:
    # deactivate all traps
    getcontext().traps = {}
    x = Decimal(request.params['x'])
    if x.is_infinite() or x.is_nan():
        # x is NaN, -Infinity or +Infinity
        pass
    else:
        # x should be a valid float
        pass