The fileExists() method will attempt to open a file for reading. If it exists, a True value will be returned from the method. If the file does not exist, a False value is returned. A string containing the file name must be passed to the method.
def fileExists (fname):
f_exists = False
try:
f=open(fname,'r')
f.close()
f_exists = True
except:
print("file '"+ fname+ "' does not exist")
return f_exists