请高手解说一下这几个sub

QUOTE:

  # One argument is true
  sub any { $_ && return 1 for @_; 0 }
  # All arguments are true
  sub all { $_ || return 0 for @_; 1 }
  # All arguments are false
  sub none { $_ && return 0 for @_; 1 }
  # One argument is false
  sub notall { $_ || return 1 for @_; 0 }
  # How many elements are true
  sub true { scalar grep { $_ } @_ }
  # How many elements are false
  sub false { scalar grep { !$_ } @_ }