Mathematica: HOWTO Find the value of a symbol in all contexts

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There is no pre-defined function for finding which contexts a symbol is defined in, but you can use the following to iterate over all known contexts and find the value of a symbol without creating any new symbols in the contexts tested:

valueInAllContexts[symbol_] := Symbol /@ Names[# <> ToString[symbol] & /@ $ContextPath]; 
Typical result for a var known globally and in two contexts:

{ContextA`var, ContextB`var,var}
Above, the var is known in each context but does not have values. If it has a value valB in, say, one of the contexts ContextB you'd get:

{ContextA`var,valB,var}
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