The attribute Unchecked_Access is used to create 
access values in an unsafe manner — the programmer is responsible 
for preventing “dangling references.” 
All rules and semantics that 
apply to X'Access (see 
3.10.2) apply also 
to X'Unchecked_Access, except that, for the purposes of accessibility 
rules and checks, it is as if X were declared immediately within a library 
package.