string.replace().replace()

def a(text):
 chars = "&#"
 for c in chars:
 text = text.replace(c, "\\" + c)
def b(text):
 for ch in ['&','#']:
 if ch in text:
  text = text.replace(ch,"\\"+ch)
import re
def c(text):
 rx = re.compile('([&#])')
 text = rx.sub(r'\\\1', text)
RX = re.compile('([&#])')
def d(text):
 text = RX.sub(r'\\\1', text)
def mk_esc(esc_chars):
 return lambda s: ''.join(['\\' + c if c in esc_chars else c for c in s])
esc = mk_esc('&#')
def e(text):
 esc(text)
def f(text):
 text = text.replace('&', '\&').replace('#', '\#')
def g(text):
 replacements = {"&": "\&", "#": "\#"}
 text = "".join([replacements.get(c, c) for c in text])
def h(text):
 text = text.replace('&', r'\&')
 text = text.replace('#', r'\#')
def i(text):
 text = text.replace('&', r'\&').replace('#', r'\#')