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local_variable_defined? 

        # Binding.local_variable_defined?

(from ruby core)
---
    binding.local_variable_defined?(symbol) -> obj

---

Returns `true` if a local variable `symbol` exists.

    def foo
      a = 1
      binding.local_variable_defined?(:a) #=> true
      binding.local_variable_defined?(:b) #=> false
    end

This method is the short version of the following code:

    binding.eval("defined?(#{symbol}) == 'local-variable'")

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