/([A-Z])\w+/g
/ab+c/
/d(b+)d/g
/\w+\s/g
/\p{L}*/u
/\b[A-Z0-9._%+-]+@[A-Z0-9.-]+\.[A-Z]{2,}\b/
/\A[a-z0-9!#$%&'*+/=?^_`{|}~-]+(?:\.[a-z0-9!#$%&'*+/=?^_`{|}~-]+)*@(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\z/
/[^aeiou]y[^aeiou]/
/r[aeiou]+/g
/seriali[sz]e/
/^[ \t]+|[ \t]+$/
/[+-]?(\d+(\.\d*)?|\.\d+)([eE][+-]?\d+)?/
/gray|grey/
/gr(a|e)y/
/ab*(c|ε)/
/(0|(1(01*0)*1))*/
/[a-z]/
/[abcx-z]/
/[]abc]/
/[^a-z]/
/[xyz]*/
/[hc]at$/
/[^b]at/
/s.*/
/[hc]?at/
/cat|dog/
/\p{Alpha}/