from manim import *  class TexTemplateFromCLI(Scene):    """This scene uses a custom TexTemplate file.    The path of the TexTemplate _must_ be passed with the command line    argument `--tex_template <path to template>`.    For this scene, you can use the custom_template.tex file next to it.    This scene will fail to render if a tex_template.tex that doesn't    import esvect is passed, and will throw a LaTeX error in that case.    """     def construct(self):        text = MathTex(r"\vv{vb}")        self.play(Write(text))        self.wait(1)  class InCodeTexTemplate(Scene):    """This example scene demonstrates how to modify the tex template    for a particular scene from the code for the scene itself.    """     def construct(self):        # Create a new template        myTemplate = TexTemplate()         # Add packages to the template        myTemplate.add_to_preamble(r"\usepackage{esvect}")         # Set the compiler and output format (default: latex and .dvi)        # possible tex compilers: "latex", "pdflatex", "xelatex", "lualatex", "luatex"        # possible output formats: ".dvi",  ".pdf", and ".xdv"        myTemplate.tex_compiler = "latex"        myTemplate.output_format = ".dvi"         # To use this template in a Tex() or MathTex() object        # use the keyword argument tex_template        text = MathTex(r"\vv{vb}", tex_template=myTemplate)        self.play(Write(text))        self.wait(1)