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based on an earlier version of the Wolfram Language.
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$MessagePrePrint

$MessagePrePrint
is a global variable whose value, if set, is applied to expressions before they are included in the text of messages.
Have expressions in messages print out in TraditionalForm:
Restore the default. Now the expressions are shown in StandardForm:
Have expressions in messages print out in TraditionalForm:
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Restore the default. Now the expressions are shown in StandardForm:
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Locally define $MessagePrePrint so that expressions sent to messages are shown in a circle:
The local definition does not affect messages outside the Block:
Make a list of all expressions sent to messages during a computation:
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