python - How does one check if a variable is a sympy expression? -

i wanted check python variable sympy expression. easy check if sympy variable with:

isinstance(arg, symbol.symbol) 

but can't find how do:

isinstance(arg, sympy.expression) 

is possible check if python variable holds sympy expression or variable?

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as quick check did:

expr2 = x-y type(expr2) <class 'sympy.core.add.add'> 

but don't want have giant series if statement clause checking each possible type of maths expression. seems redundant/silly.

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it nice able detect when variable of type of sympy related thing , act on (and maybe later check if expression or more detailed...)

i think need sympy.expr instead of sympy.expression:

in [164]: expr2 out[164]: x - y  in [165]: type(expr2) out[165]: sympy.core.add.add 

but if @ __bases__ of type:

in [166]: type(expr2).__bases__ out[166]: (sympy.core.expr.expr, sympy.core.operations.assocop) 

and so:

in [167]: isinstance(2, sympy.expr) out[167]: false  in [168]: isinstance(x, sympy.expr) out[168]: true  in [169]: isinstance(x-y, sympy.expr) out[169]: true