.isNaN(obj)


# Is a given value equal to null?
_.isNull = (obj) -> obj is null


# Is a given variable undefined?
_.isUndefined = (obj) -> typeof obj is 'undefined'


# Utility Functions
# -----------------

# Run Underscore.js in noConflict mode, returning the `_` variable to its
# previous owner. Returns a reference to the Underscore object.
_.noConflict = ->
  root._ = previousUnderscore
  this


# Keep the identity function around for default iterators.
_.identity = (value) -> value


# Run a function 