Examples of Free Lie Algebra

In wikipedia, free Lie algebras are defined using the universal property. Can anyone give some concrete examples of free Lie algebras?

“In mathematics, a free Lie algebra, over a given field $K$, is a Lie algebra generated by a set $X$, without any imposed relations.” If we take the field $K$ to be the field $\mathbb{C}$ of complex numbers, what is the free algebra if

  1. $X=\emptyset$?
  2. $X=\{0\}$?
  3. $X=\{0,1,2\}$?
  4. $X=\mathbb{R}$?
  5. $X=\mathbb{C}$?

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