clientv3/compare.go
func (cmp Cmp) WithPrefix() Cmp {
	cmp.RangeEnd = getPrefix(cmp.Key)
	return cmp
}
func (cmp Cmp) WithPrefix() Cmp {
	cmp.RangeEnd = getPrefix(cmp.Key)
	return cmp
}
func ( cmp Cmp ) WithPrefix ( ) Cmp { cmp . RangeEnd = getPrefix ( cmp . Key ) return cmp }
// WithPrefix sets the comparison to scan all keys prefixed by the key.
WithPrefix sets the comparison to scan all keys prefixed by the key .