Reference for Functional Analysis I am in search for Functional Analysis Books.

I need a book which have lots of elementary problems.

I mean it should force us to think more which will give a deeper insight for functional analysis.

To be precise, I need lots of problems like Is $A$ open in the space $\ell^1$ with respect to norm $\|.\|_2$. Find a counterexample to this statement and etcetera.

I mean it shouldn't ask us trivial questions. It should ask us questions which will force us to think more and more from functional analysis
The most elementary book for functional analysis I've seen is Introductory functional analysis of E.Kreyszig, really really understandable and its problems are 'basics'.
If you're new, try Simmons's book. Other than that both books of Walter Rudin and John B. Conway consists of many non-trivial questions. P.R. Halmos's "A Hilbert Space Problem Book" by springer is difficult to me atleast.