$7\ Arrow\ Symbols$
$\leftarrow$ \leftarrow
$\Leftarrow$ \Leftarrow
$\rightarrow$ \rightarrow
$\Rightarrow$ \Rightarrow
$\leftrightarrow$ \leftrightarrow
$\Leftrightarrow$ \LeftRightarrow
$\mapsto$ \mapsto
$\hookleftarrow$ \hookleftarrow
$\leftharpoonup$ \leftharpoonup
$\leftharpoondown$ \leftharpoondown
$\rightleftharpoons$ \rightleftharpoons