git ssb

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function isFunction (fun) {
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  return 'function' === typeof fun
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}
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//check if this stream is either a sink or a through.
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function isReader (fun) {
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  return isFunction(fun) && (fun.length === 1)
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}
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module.exports = function pull () {
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  var args = [].slice.call(arguments)
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  if(isReader(args[0]))
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    return function (read) {
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      args.unshift(read)
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      return pull.apply(null, args)
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    }
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  var read = args.shift()
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  //if the first function is a duplex stream,
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  //pipe from the source.
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  if(read && isFunction(read.source))
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    read = read.source
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  function next () {
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    var s = args.shift()
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    if(null == s)
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      return next()
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    if(isFunction(s)) return s
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    return function (read) {
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      s.sink(read)
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      //this supports pipeing through a duplex stream
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      //pull(a, b, a) "telephone style".
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      //if this stream is in the a (first & last position)
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      //s.source will have already been used, but this should never be called
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      //so that is okay.
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      return s.source
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    }
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  }
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  while(args.length)
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    read = next() (read)
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  return read
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}
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