Sparse is not defined

When I try to run W = sparse(W + W’);
it gives the following error.

UndefVarError: sparse not defined

Stacktrace:
[1] top-level scope
@ In[13]:21
[2] eval
@ .\boot.jl:368 [inlined]
[3] include_string(mapexpr::typeof(REPL.softscope), mod::Module, code::String, filename::String)
@ Base .\loading.jl:1428

Type using SparseArrays first.