字符串replace

    def replace(self, old, new, count=None): # real signature unknown; restored from __doc__
        """
        S.replace(old, new[, count]) -> str
        
        Return a copy of S with all occurrences of substring
        old replaced by new.  If the optional argument count is
        given, only the first count occurrences are replaced.
        """
        return ""

name="wesley hello world wesley wesley"
ret=name.replace('wesley','miao')
print(ret)
ret=name.replace('wesley','miao',1)
print(ret)
ret=name.replace('wesley','miao',2)
print(ret)

miao hello world miao miao  #全部替换
miao hello world wesley wesley
miao hello world miao wesley           #count,找到3个，根据count只替换前两个