Found the following HTML validation problems:
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SLT.html:210:1 (SLT.Rd:128): Warning: <h5> anchor "Arguments" already defined
SLT.html:225:1 (SLT.Rd:137): Warning: <h5> anchor "Returns" already defined
SLT.html:242:1 (SLT.Rd:146): Warning: <h5> anchor "Usage" already defined
SLT.html:248:1 (SLT.Rd:150): Warning: <h5> anchor "Arguments" already defined
SLT.html:263:1 (SLT.Rd:159): Warning: <h5> anchor "Returns" already defined
SLT.html:288:1 (SLT.Rd:176): Warning: <h5> anchor "Usage" already defined
SLT.html:294:1 (SLT.Rd:180): Warning: <h5> anchor "Arguments" already defined
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SLT.html:396:1 (SLT.Rd:250): Warning: <h5> anchor "Arguments" already defined
SLT.html:418:1 (SLT.Rd:266): Warning: <h5> anchor "Returns" already defined
SLT.html:439:1 (SLT.Rd:279): Warning: <h5> anchor "Usage" already defined
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SLT.html:539:1 (SLT.Rd:343): Warning: <h5> anchor "Usage" already defined
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SLT.html:823:1 (SLT.Rd:527): Warning: <h5> anchor "Usage" already defined
SLT.html:829:1 (SLT.Rd:531): Warning: <h5> anchor "Returns" already defined
SLT.html:846:1 (SLT.Rd:540): Warning: <h5> anchor "Usage" already defined
SLT.html:852:1 (SLT.Rd:544): Warning: <h5> anchor "Arguments" already defined
dir_tree.html:54:1 (dir_tree.Rd:14): Warning: missing </ul> before </div>