# [Python 3], <s>52</s> 48 bytes

<!-- language-all: lang-python -->

    lambda a,b:[a,b,*range(a+(a<b)*2-1,b,(a<b)*2-1)]

[Try it online!][TIO-jo8fxo26]

[Python 3]: https://docs.python.org/3/
[TIO-jo8fxo26]: https://tio.run/##VU7LDoIwELz7FZN4aXGbyKNAjH4JcihRlEQrIVz8@rotCnjYzXTn0enf4/1lU9eezu5hns3FwFBzqHhRNBh7uwqzE@bYyChRMR9nLGvXD50dRSuwJ0BLiS0qhpoQExJCSsjqzU@l@IlyUnlcEhSLONX7F0cIyAnFYvVHZJM1@wsNjJ4ZvWI4H8nElCG8CLE6fJGuevkSxbdXwDxcRLFMsVrltfsA "Python 3 – Try It Online"

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<b>EDITED</b> :  remove c and switch to lambda function. Credits to @Jo King.