Extensible arrows - LaTeX symbols

Symbol Command
$\xrightarrow{something}$ \xrightarrow{something}
$\xRightarrow{something}$ \xRightarrow{something}
$\xmapsto{something}$ \xmapsto{something}
$\xrightharpoonup{something}$ \xrightharpoonup{something}
$\xrightharpoondown{something}$ \xrightharpoondown{something}
$\xhookrightarrow{something}$ \xhookrightarrow{something}
$\xtwoheadrightarrow{something}$ \xtwoheadrightarrow{something}
Symbol Command
$\xleftarrow{something}$ \xleftarrow{something}
$\xLeftarrow{something}$ \xLeftarrow{something}
$\xleftharpoonup{something}$ \xleftharpoonup{something}
$\xleftharpoondown{something}$ \xleftharpoondown{something}
$\xhookleftarrow{something}$ \xhookleftarrow{something}
$\xtwoheadleftarrow{something}$ \xtwoheadleftarrow{something}
Symbol Command
$\xleftrightarrow{something}$ \xleftrightarrow{something}
$\xtofrom{something}$ \xtofrom{something}
$\xrightleftharpoons{something}$ \xrightleftharpoons{something}
$\xleftrightharpoons{something}$ \xleftrightharpoons{something}
$\xlongequal{something}$ \xlongequal{something}

LaTeX arrow

LaTeX