Can I pass an arbitrary block of commands to a bash function?

function conditional-do {
    if [ -f $1 ]
    then
        echo "Doing stuff"
        $2
    else
        echo "File doesn't exist!"
    end
}

function exec-stuff {
    echo "do some command"
    echo "do another command"
}
conditional-do /path/to/file exec-stuff

function file_exists {
  if ( [ -e $1 ] ) then
    echo "Doing stuff"
  else
    echo "File $1 doesn't exist"
    false
  fi
}

file_exists filename && (
  echo "Do your stuff..."
)

file_exists filename && echo "Do your stuff..."

function file_exists {
  if ( [ -e $1 ] ) then
    echo "Doing stuff"
    shift
    $*
  else
    echo "File $1 doesn't exist"
    false
  fi
}

file_exists filename echo "Do your stuff..."

[ -f $filename ] && echo "it has worked!"

function file-exists {
    [ "$1" ] && [ -f $1 ]
}

file-exists $filename && echo "It has worked"