latex header

header.tex

\documentclass{article}

\usepackage[english]{babel}

\usepackage[letterpaper,top=3cm,bottom=3cm,left=4cm,right=4cm,marginparwidth=1.75cm]{geometry}
\usepackage{amsmath,amssymb,amsfonts}
\newcommand{\pr}{\mathbb{P}}
\newcommand{\E}{\mathbb{E}}
\newcommand{\eps}{\epsilon}
\newcommand{\R}{\mathbb{R}}
\usepackage{enumitem}
\setlist[itemize]{label=$\circ$}

\usepackage{amsmath}
\usepackage{graphicx}
\usepackage{lipsum}
\usepackage[colorlinks=true, allcolors=blue]{hyperref}