Do you mean something similar to
class function:
def createtextfile(self, text):
f = open('foo.txt','w')
f.write(text)
f.close()
def addtext(self):
f = open('foo.txt','a')
something = input('what would you like to add? ')
f.write(something)
f.close()
def readtext(self):
justread = open('foo.txt','r').read()
print(justread)
f = function()
f.createtextfile("foo\n")
f.addtext()
f.readtext()