Extensions - Mailing list pgsql-general

I have a doubt regarding the extensions.My db has these many extensions

        Name      
-------------------
 adminpack        
 btree_gist        
 dblink            
 file_fdw          
 fuzzystrmatch    
 hstore            
 insert_username  
 intarray          
 pageinspect      
 pg_buffercache    
 pg_freespacemap  
 pg_repack        
 pg_stat_statements
 pg_trgm          
 pgcrypto          
 plpgsql          
 unaccent          

How can i figure out what all extensions are being used ? is there any way ?

Thanks,

Bhargav